Grid Interconnecting Solar Generation System Using Transformer Less Cascaded Seven Level Inverter

Abstract

Multilevel inverter is a power electronic device that is used for high voltage and high power applications and has many advantages like, low switching stress, low total harmonic distortion (THD). Hence, the size and bulkiness of passive filters can be reduced. This paper proposes three topologies of a 7- level cascaded multilevel inverter with reduced number of switches with the 5-level cascaded multilevel inverter and 3-level inverter. The topologies consist of circuits with 9 switches for 7-level CMLI, 8 switches for the 5-level CMLI and 6 switches for the 3-level inverter. Apart from the reduction in switch count this paper also includes minimization of leakage currents and comparative analysis of levels of CMLI’s in every inverter connected to PV source. The control scheme based on Sinusoidal Pulse Width Modulation (SPWM) is adopted due to its ease of implementation. More number of levels results in reduced THD and nearly sinusoidal output. Simulation is performed using Matlab/Simulink.